Premium
Measurement of topcoat thickness of thermal barrier coating for gas turbines using terahertz waves
Author(s) -
Fukuchi Tetsuo,
Fuse Norikazu,
Fujii Tomoharu,
Okada Mitsutoshi,
Fukunaga Kaori,
Mizuno Maya
Publication year - 2013
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.22385
Subject(s) - thermal barrier coating , materials science , terahertz radiation , refractive index , optics , refraction , composite material , coating , optoelectronics , physics
The topcoat thickness of thermal barrier coating (TBC) samples was measured using terahertz (THz) waves. The index of refraction of yttria‐stabilized zirconia (YSZ), which is the topcoat material, is necessary to obtain the topcoat thickness from time domain reectometry. Time domain THz spectroscopy was applied to YSZ samples, and the index of refraction was measured to be 4.8 in the frequency region 0.1 to 1.2 THz. The topcoat thickness of six dierent TBC samples, which varied from 300 to 600 µm, was measured using THz waves. The results were in agreement with microscope observation results to within measurement error. In addition, the topcoat thickness prole of a turbine blade sample was measured with a resolution of 2.4 µm. The prole showed a standard deviation of 4 µm, which reects the actual variation in the topcoat thickness. The results showed that THz waves are eective for high‐resolution measurement of the topcoat thickness. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 1–9, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22385